Data processing system and data processor

ABSTRACT

One data processor is provided with an interface for realizing connection with the other data processor. This interface is provided with a function for connecting the other data processor as a bus master to an internal bus of the one data processor, and the relevant other data processor is capable of directly operating peripheral functions that are memory mapped to the internal bus from an external side via the interface. Accordingly, the data processor can utilize the peripheral functions of the other data processor without interruption of the program being executed. In short, one data processor can use in common the peripheral resources of the other data processor.

This application is a continuation of U.S. patent application Ser. No.14/057,442, filed Oct. 18, 2013; which is a continuation of U.S. patentapplication Ser. No. 13/555,786, filed Jul. 23, 2012, now U.S. Pat. No.8,595,388; which is a continuation of U.S. patent application Ser. No.13/025,785, filed Feb. 11, 2011, now U.S. Pat. No. 8,244,926; which is acontinuation of U.S. patent application Ser. No. 12/470,988, filed May22, 2009, now U.S. Pat. No. 7,975,077; which is a continuation of U.S.patent application Ser. No. 12/155,412, filed Jun. 4, 2008, now U.S.Pat. No. 7,725,616; which is a continuation of U.S. patent applicationSer. No. 11/203,210, filed Aug. 15, 2005, now U.S. Pat. No. 7,401,165;which is a continuation of U.S. patent application Ser. No. 10/470,758,filed Jul. 31, 2003, now U.S. Pat. No. 7,401,163; which is a 371 ofinternational application No. PCT/JP2001/009322, filed Oct. 24, 2001,the contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a data transfer system for busconnecting data processors and to a data transfer system for use in asystem formed of a plurality of data processors and a plurality ofsystem buses. For example, the present invention relates to a techniquein which a data processor uses, in common, the built-in circuits ofother data processors, and to a technique in which a data processormakes access to the external buses of other data processors. Moreover,the present invention relates to a technique for boot control in whichan operation program of a data processor is initially stored in memory.

With the development of more complicated systems, the number of dataprocessors and components mounted in a system is increasing. Forexample, in a mobile phone system, a baseband data processor forcontrolling communication has been used to control software (applicationand key control or the like) and hardware (components of RF circuit, LCDand memory or the like). However, with diversification of functions, itis now difficult for the baseband processor to perform all processes. Ina known PC system, this problem has been solved by improving theoperating frequency of the data processor, but in a battery-driven typemobile terminal it is not possible to simply improve the performancewith use of a higher frequency, because, for such purpose, the operatinglife of the battery must be expanded.

It has also been proposed to use a method to vary the frequency with theprocesses that are being executed by the data processor, but realizationof such a technique in practical use is difficult, because actualrealization is very difficult in the system. Moreover, a data processorwhich can realize high speed operation tends to become large in the chiparea, and it is also difficult to reduce the current value during thestandby state.

In order to solve this problem, applications which cannot be processedwith available data processors of the prior art have been processedusing a co-processor or another data processor. Accordingly, since it ispossible to operate only data processors that are suitable forparticular processes, when such particular processes are required, thesystem can be formed easily, and, finally, a reduced power consumptionof the system as a whole can also be realized.

When a plurality of data processors, such as a data processor and aco-processor or the like, are mounted in one system, a common bus isfrequently used for connection of the data processors. However, when adata processor which cannot use a common bus is used, and when fullperformance cannot be exhibited through common use of a bus because thememory access performance is insufficient, it is required to conduct thedata transfer by providing a certain interface to one data processor andthen connecting this interface to the bus of the other processor. Asthis interface, there is a host port interface supported, for example,by the DSP (TMS320C54x) of TI. In actual practice, data transfer isperformed between data processors by utilizing the RAM built in the dataprocessor and the interruption function of the processor. However,software must be executed to use the data transferred.

Not only the system, but also the function itself of the data processor,are highly sophisticated. When a plurality of data processors aremounted to the system, it is not required for a plurality of dataprocessors to support the same duplicated function, by efficiently usingthe functions mounted to the data processors, such as memory interface,USB (universal serial bus), memory card, serial interface for SDRAM(Synchronous DRAM) or the like. When data processors are connected withan interface not depending on the common bus, the data transferred mustbe processed with software under the condition that the functionssupported by the respective data processors are used. For example, whena certain data processor desires to make access to a memory by utilizinga memory interface of another data processor, it has been required thatthe data to be accessed with the above-mentioned interface is firsttransferred to another data processor, a program of the other dataprocessor is thereafter executed as an interruption process, thereby theother data processor in the execution of such a program makes access toa memory, and the other data processor issues, after such access, aninterruption to the one data processor for effecting the data transferto the one data processor via the interface.

As another problem resulting from the complicated system structure,reduction of the mounting area may be listed. Particularly, at a mobileinformation terminal, it is required to reduce the number of componentsused in the system in order to reduce the mounting area, from theviewpoint of reduction in power consumption and cost. However, when thesystem is improved so as to have multiple functions, the number ofcomponents also increases so as to realize such functions. Particularly,when a plurality of data processors are comprised as described above,this problem becomes more serious.

In the case where a plurality of data processors are mounted on thesystem, as described in regard to the technology of the prior art, andsuch data processors cannot be connected with a common bus, it isrequired to provide an interface for mutually connecting the dataprocessors. The host interface, such as a DSP of TI, performs handshakeoperations to realize data transfer by utilizing the RAM built in thedata processor and the interruption function of the processor. In usingthis method, since it is required to execute the interruption processprogram for every data transfer, the performance may be deterioratedbecause the execution of the program currently being operated isinterrupted. Particularly, a problem arises when it is required to useonly an external interface supported by the data processor.

Moreover, the inventors of the present invention have considered thetechnology used to initially store an operation program of a dataprocessor to a memory. For example, in a microprocessor where anelectrically reprogrammable flash memory is formed on a chip to storethe operation program of the CPU, an initial program for such flashmemory is generally written, for example, using, in its fabricationstage, a writing device, such as an EPROM writer. However, such a writeoperation is complicated, and, moreover, it takes a longer time becausesuch a write operation is accompanied by a verify process and a rewriteprocess. Therefore, this write operation is also considered as a causeof a rise in the fabrication cost of a data processor.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to realize a dataprocessor which has a data transfer interface for data transfer, inaddition to a memory interface, in a data processing system which iscomplicated due to its ability to perform multiple functions.

Moreover, the present invention has another object to effectively usethe internal function of a relevant data processor, or external circuitsof the relevant data processor, from another data processor or deviceconnected to such interface. Moreover, the present invention is intendedto finally realize low power consumption through improvement of systemperformance and realization of low cost.

A further object of the present invention is to provide a dataprocessing system and, moreover, a data processor which can easilyrealize a process to initially write a program to be executed by thedata processor to a nonvolatile memory.

The above-mentioned and other objects and novel features of the presentinvention will become more apparent from the description provided in thepresent specification and from the accompanying drawings.

The typical aspects of the invention disclosed in this specificationwill be briefly described below.

[1] According to a first aspect of the present invention, an internalbus access of a data processor is allowed to other data processors.

According to this first aspect of the present invention, a dataprocessor (100) is provided with an interface (119) to enable connectionwith another data processor (101) and this interface is provided with afunction to connect the other data processor as a bus master to theinternal bus of one data processor to support the function to directlyoperate a peripheral function that is memory-mapped to the internal buswith the relevant other data processors from an external side via theinterface. Thereby, the data processor is capable of utilizing theperipheral functions of the other data processor without interruption ofthe programs being executed therein. When the first data processor makesaccess, for example, to a particular memory using the memory interfaceof a second data processor, the first data processor is capable ofmaking access and then using the peripheral memory and the otherperipheral circuits via the interface of the second data processor. Inshort, one data processor can use in common the peripheral resources ofthe other data processors. In other words, the first data processor candirectly use the other interface function provided in the second dataprocessor. Thereby, high performance of the system can be realized.

The invention according to above-described aspect will be described infurther detail. The data processing system according to the first aspectincludes the first data processor (100) and the second data processor(101). The second data processor comprises the interface (119) whichallows the first data processor to obtain the right to use the internalbus of the second data processor. The interface causes the first dataprocessor having obtained the right to use the internal bus, to makeaccess to an input/output circuit that is connected to the internal bus.

The input/output circuit is formed of a single circuit or of a pluralityof circuits selected, for example, from a SDRAM interface circuit thatis connected to a SDRAM, an LCD interface circuit that is connected to aliquid crystal display device, a memory card interface circuit that isconnected to a memory card, a serial interface circuit, a nonvolatilememory, an electrically reprogrammable nonvolatile memory and a generalpurpose input/output port circuit.

The interface may include a buffer RAM (107) which exclusively respondsto carry out access from the second data processor and access from thefirst data processor.

[2] According to a second aspect of the present invention, the otherdata processor is allowed to make access to the inherent external bus ofthe one data processor via the relevant one data processor.

The present invention according to this second aspect is provided with adevice (114) which enables an interface, within the second dataprocessor, to effect connection between the first data processor (100)and the external device (104) of the relevant second data processor,while the second processor (101) is in the waiting condition (powersupply is off or in a standby state). Accordingly, the first dataprocessor is capable of controlling the device connected to the seconddata processor without use of an external circuit during the waitingcondition of the relevant second data processor. In short, even when thesecond data processor is in the waiting condition, the first dataprocessor is capable of controlling the external circuit connected tothe relevant second data processor by bypassing the internal circuits ofthe second data processor. Thereby, the number of components forming thedata processing system can be reduced, and reduction in cost can also berealized.

The invention based on the above-described aspect will be described infurther detail. The data processing system according to the secondaspect includes the first data processor (100), a first bus (103)connected to the first data processor, the second data processor (101)connected to the first bus, and a second bus (105) connected to thesecond data processor. The second data processor includes a firstexternal interface circuit (119) which is connected to the first bus atone terminal and to the internal bus at the other terminal, a secondexternal interface (113) which is connected to the second bus at oneterminal and to the internal bus at the other terminal, and a switchcircuit (114) for connecting the one terminal of the first interfacecircuit to the second bus in place of the one terminal of the secondexternal interface circuit, while the second data processor is in thewaiting condition.

In the waiting condition of the second data processor, the supply of aclock signal, for example, to a clock synchronization circuit includedin the second data processor is suspended. Moreover, a power supplycontrol circuit (116 b) is also included in the second data processor toseparate the operation power supply of the switch circuit from theoperation power supply of the other circuits and to suspend the supplyof the operation power supply to a part or the entire part of theabove-described and the other circuits in response to the waitingcondition of the second data processor. Thereby, the power consumptionmay be reduced in the waiting condition of the second data processor.

The second external interface circuit includes an LCD interface circuitwhich can be connected, for example, to a liquid crystal displaycontroller. In this case, the second bus is connected with the liquidcrystal display controller. Accordingly, the first data processor iscapable of controlling the liquid crystal display controller via theswitch circuit.

[3] According to a third aspect, operation control for initially writingan operation program, to be executed with a data processor, after areset operation is cancelled, to an on-chip nonvolatile memory andnonvolatile memory on the local bus may be realized via the relevantdata processor.

The data processing system of the present invention, according to thisthird aspect, includes the first data processor (100) and the seconddata processor (101). The second data processor includes a nonvolatilememory (107) which is controlled to write the data with the first dataprocessor in a first operation mode after the reset operation iscancelled, a CPU (109) which considers the nonvolatile memory as anobject of instruction fetch after the write operation in the firstoperation mode, and an electrically reprogrammable nonvolatile memory(502) which is considered as the object of instruction fetch by the CPUin the second operation mode after the reset operation is cancelled. Thefirst data processor designates the first operation mode to the seconddata processor, and then it stores, to the nonvolatile memory, a writecontrol program for the nonvolatile memory and allows the CPU to fetchan instruction. Accordingly, the second data processor is capable ofexecuting the write control program that is written to the nonvolatilememory and then of initially writing the operation program of the firstdata processor to the on-chip nonvolatile memory depending on suchexecution. It is sufficient for execution of this operation program thatthe second operation mode is designated after the reset operation iscancelled.

The electrically reprogrammable nonvolatile memory is never limited tothe on-chip memory of the first data processor. This memory may be anelectrically reprogrammable nonvolatile memory (501) connected to thelocal bus of the first data processor.

According to the third aspect, operation control to initially write theoperation program, to be executed by the data processor, after the resetoperation is cancelled, to the on-chip nonvolatile memory and thenonvolatile memory on the local bus can be realized via the relevantdata processor. In short, it is no longer required to execute theprocess to write the program to the on-chip program memory or the likein the fabrication process of the data processor.

[4] A fourth aspect of the present invention is directed to the dataprocessor to be applied to the data processing system based on the firstto third aspects described above.

A data processor includes a CPU (109), an internal bus connected to theCPU, a peripheral circuit (116) connected to the internal bus, the firstexternal interface circuit (119) connected to a first external terminalat one terminal thereof and to the internal bus at the other terminal,and the second external interface circuit (113) connected to a secondexternal terminal at one terminal thereof and to the internal bus at theother terminal thereof. The first external interface circuit obtains theright to use the internal bus in response to an external access requestand enables access to the peripheral circuit that is connected to theinternal bus. Accordingly, a data processor is capable of allowing theother data processors to use the on-chip peripheral circuits connectedto the internal bus.

Moreover, the switch circuit (114) for connecting the first externalterminal to the second external terminal in place of the second externalinterface circuit during the waiting condition of the CPU may also beincluded. The other data processors are allowed, via the relevant onedata processor, to make access to the inherent external bus of the onedata processor. For example, when an LCD controller is connected to thelocal bus of a data processor, the other data processor can realize atime display control function for the LCD via the LCD control on thelocal bus via the system bus when the relevant data processor is in thewaiting condition.

According to the third aspect of the present invention, whereby a bootprogram of data processor is initially written, a data processor furtherincludes a nonvolatile memory which is externally written via the firstexternal interface circuit in the first operation mode after the resetoperation is cancelled, and a program memory such as an electricallyreprogrammable nonvolatile memory. The CPU can fetch an instruction fromthe nonvolatile memory after the write operation in the first operationmode and then execute such instruction; and, moreover, the CPU can fetchthe instruction from the program memory in the second operation modeafter the reset operation is cancelled and then execute thisinstruction. The boot program of the data processor can be initiallywritten to the nonvolatile program memory by writing a write controlprogram for the program memory to the nonvolatile memory in the secondoperation mode and then executing the written write control program inthe second operation mode.

A data processor can be configured with a single chip by forming, on onesemiconductor substrate, the CPU, internal bus, first external interfacecircuit, second external interface circuit, switch circuit, nonvolatilememory and program memory. Moreover, it is also possible to form amulti-chip module by forming, on the first semiconductor substrate, theCPU, internal bus, first external interface circuit, second externalinterface circuit, switch circuit and nonvolatile memory, forming theprogram memory (501) on the second semiconductor substrate, and mountingboth first and second semiconductor substrates, for example, on a highdensity mounting substrate to form a sealed package.

[5] According to a fifth aspect of the present invention, a dataprocessor to be applied to the data processing system based on the firstaspect is considered from another aspect.

A data processor includes a first terminal connected to a first bus, asecond terminal connected to a second bus, a first internal circuit anda second internal circuit, which can selectively take on a firstcondition or a second condition, a first signal route connected to thesecond terminal from the first terminal via the first internal circuitand second internal circuit, and a second signal route connected to thesecond terminal from the first terminal via the second internal circuit.The second internal circuit selects a desired signal route from thefirst signal route or second signal route depending on the condition ofthe first internal circuit.

The first condition is, for example, the operating condition to beexecuted by the first internal circuit, while the second condition is,for example, the waiting condition in which the execution ofinstructions is suspended. The second internal circuit selects the firstroute in the operating condition and also selects the second route inthe waiting condition.

Moreover, a power supply control circuit is also provided to control thesupply of a first power source to the first internal circuit and tosupply of a second power source to the second internal circuit. In thiscase, the power supply control circuit stops, when the second signalroute is selected for the second internal circuit, to stop supply fromthe first power source to the entire part or a part of the firstinternal circuit. In short, in the waiting condition, supply of uselessoperating power to the circuit which is not requested to operate isstopped.

The first internal circuit, second internal circuit and power supplycontrol circuit may be formed on one semiconductor substrate. Moreover,it is also possible that the first internal circuit and power supplycontrol circuit are formed on the first substrate, the second internalcircuit is formed on a second semiconductor substrate, and the first andsecond semiconductor substrates are sealed in one package. Thereby, adata processor can be formed as a multi-chip module or the like.

When the first internal circuit includes a clock control circuit (116 a)to supply a clock signal for synchronous operation to the first internalcircuit, it is recommended that the clock control circuit stops supplyof the clock signal to the first internal circuit when the second signalroute is selected by the second internal circuit. In the waitingcondition, it is more desirable to stop the supply of the clock signalto the circuit which is not required to operate in order to preventuseless power consumption.

As a desirable profile, the power supply control circuit for controllingsupply of the first power source to the first internal circuit and forsupply of the second power source to the second internal circuit stopsthe supply of power to the entire part or a part of the first internalcircuit when the supply of the clock signal to the first internalcircuit is stopped.

The first internal circuit, second internal circuit, clock controlcircuit and the power supply control circuit may be formed on onesemiconductor substrate. Moreover, the first internal circuit, clockcontrol circuit and power supply control circuit may be formed on thefirst semiconductor substrate, the second internal circuit may be formedon a second semiconductor substrate, and the first semiconductorsubstrate and the second semiconductor substrate may be sealed in onepackage to form a multi-chip module of the data processor.

[6] According to a sixth aspect of the present invention, theinformation processing system based on the first aspect will beconsidered from a different aspect.

An information processing system comprises a first bus, a second bus anda data processor connected to the first bus and the second bus. The dataprocessor has a first operation profile and a second operation profile.In the first operation profile, the data processor processes theinformation supplied from the first bus and supplies the predeterminedinformation to the second bus. In the second operation profile, the dataprocessor directly supplies the information from the first bus to thesecond bus.

Moreover, according to another aspect of the present invention, a mobilephone system comprises first to third semiconductor integrated circuits,a first bus for connecting the first semiconductor integrated circuitand the second semiconductor integrated circuit, and a second bus forconnecting the second semiconductor integrated circuit and the thirdsemiconductor integrated circuit. The second semiconductor integratedcircuit includes a first operation profile and a second operationprofile. In the first operation profile, the second semiconductorintegrated circuit performs a predetermined process based on theinformation supplied from the first semiconductor integrated circuit andsupplies the result of process to the third semiconductor integratedcircuit. In the second operation profile, the second semiconductorintegrated circuit supplies the information supplied from the firstsemiconductor integrated circuit directly to the third semiconductorintegrated circuit.

In the mobile phone system described above, the first semiconductorintegrated circuit may supply a control signal which controls the secondsemiconductor integrated circuit to be shifted to any one of the firstand second operation profiles. Such control signal may be given as acommand.

In the mobile phone system, the first semiconductor integrated circuitis provided, for example, for processing of the baseband, while thesecond semiconductor integrated circuit is provided for display control.The predetermined processes are performed, for example, for at least thevideo signals.

A storage device may be connected to the second bus. For example, thestorage device may store a processing program which specifies theprocesses to be executed in the second semiconductor integrated circuit.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating an example of the data processingsystem of the present invention.

FIG. 2 is a block diagram illustrating in detail a bypass region in thesecond data processor of FIG. 1.

FIG. 3 is a block diagram illustrating an example in the case where adata processor is formed of a multi-chip module.

FIG. 4 is a block diagram illustrating a practical example of a firstexternal interface circuit provided in the second data processor of FIG.2.

FIG. 5 is a block diagram of another practical example of the firstexternal interface circuit provided in the second data processor.

FIG. 6 is a block diagram illustrating the initial write operation of aboot program of the data processor in the data processing system of thepresent invention.

FIG. 7 is a timing diagram of the boot operation in the data processingsystem of FIG. 6.

FIG. 8 is another timing diagram of the boot operation in the dataprocessing system of FIG. 6.

FIG. 9 is a timing diagram of the operation for updating a boot programor adding/updating applications executed by the second data processor inthe condition that the boot program is stored in the program memory.

FIG. 10 is a cross-sectional view of a multi-chip module which forms thedata processor of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates an example of the data processing system of thepresent invention. This system is composed of a first data processor 100that is connected to a first external bus 103 and a second dataprocessor 101 that is connected to a second external bus 105. The firstexternal bus 103 is connected with a plurality of external devices 102,such as a RAM, ROM and flash memory (FLASH). The second external bus 105is connected with external devices 104, such as a RAM, ROM, FLASH, and aliquid crystal display (LCD) controller. The second data processor 101is connected to the first external bus 103 via a first externalinterface circuit 119 as a device on the first external bus 103.

The second data processor 101 includes an internal high-speed bus 108and an internal low-speed bus 115. The internal high-speed bus 108 isconnected with a CPU 109, a cache memory 110, a digital signal processor(DSP) 111, a bridge circuit 112, which serves as a bus bridge circuitbetween the internal high-speed bus 108 and internal low-speed bus 115,the first external interface circuit 119, a second external interfacecircuit 113 and a RAM 107. The internal low-speed bus 115 is connectedwith various circuits 116, such as a serial interface circuit (SCI), aUSB (Universal Serial Bus), a timer, a memory card interface circuit(MCIF), a general purpose input/output port (IOP), such as an IO port, aclock pulse generator (CPG) and a peripheral circuit, such as flashmemory. In FIG. 1, the clock pulse generator (CPG) is identified by thereference numeral 116 a and the general purpose Input/output port (IOP)is identified by the reference numeral 116 b.

The data processing system is configured, although the invention is notparticularly so restricted, as a mobile phone system. In this case, thefirst data processor 100 performs the baseband process. The second dataprocessor 101 controls video display for the external device 104, suchas a liquid crystal display controller, and performs signal processing,such as compression and expansion of a signal. Controls, such as thedisplay of time, via the liquid crystal display controller areperformed, although the invention is not particularly so restricted, bythe first data processor 100 via the second data processor 101.

The first external interface circuit 119 allows the first data processor100 to obtain the right for use of the internal bus of the second dataprocessor, for example, the high-speed bus 108, and it also allows thefirst data processor 100, having obtained the right for use of theinternal bus 108, to access an input/output circuit connected to theinternal bus 108. The input/output circuit is a register or the like ofthe DSP 111. In short, the first data processor 100 is allowed tooperate as a bus master of the internal high-speed bus 108. Thisoperation as a bus master is controlled by the internal bus control unit106.

Moreover, the first external interface circuit 119 controls operation ofthe RAM 107, which serves as a common memory or a common buffer of theCPU 109 and first data processor 100. Namely, this first externalinterface circuit 119 operates the RAM 107 exclusively in response tothe access request to the RAM 107 from the CPU and to the access requestto the RAM 107 from the first data processor 100. With the common bufferfunction to this RAM 107, data transfer can be realized between thefirst data processor 100 and the second data processor 101. For thisdata transfer, handshake control, for example, may be employed using aninterruption signal 117. In more detail, when data is stored to the RAM107 from the first data processor 100, the interruption signal 117 ofthe CPU 109 is given and the CPU 109 fetches the data of RAM 107 withthe interruption process responding to such interruption. In the inverseoccasion, the external interface circuit 119 issues an interruptionrequest to the first data processor 100.

The second external interface circuit 113 has the interfacespecification to realize the interface operation for the externaldevices connected to the external bus 105. For example, when it isassumed that the FLASH and liquid crystal display (LCD) controller areconnected as external devices 104, the second external interface circuit113 performs the interface function for the flash memory interfacecircuit and LCD interface circuit.

In the structure of FIG. 1, a region 118 is provided with a switchcircuit 114 for connecting the external bus 103, at the first externalinterface circuit, to the external bus 105, in place of the connectingthe external bus 105 to the second external interface circuit 113, whilethe second data processor 101 is in the waiting condition. Namely, theswitch circuit 114 selects the connection profile to connect the firstexternal bus 103 to the second external bus 105 in place of the secondexternal interface circuit 113, while the second data processor 101 isin the waiting condition. Accordingly, the first data processor 100 iscapable of making access to a device on the second external bus 105 viathe switching control unit 114. For example, the first data processor100 is capable of controlling the liquid crystal display controller,which is present as the external device 104 on the external bus 105, viathe switch circuit 114. Here, the circuit in the region 118 of FIG. 1operates when the second data processor 101 is in the waiting condition.

In the waiting condition of the second data processor 101, supply of theclock signal to the CPU 109, DSP 111, serial interface circuit and clocksynchronization circuit, such as the timer included in the relevantsecond data processor 101, is stopped. For example, when the CPU 109sets a waiting condition enable bit to a waiting condition register ofthe clock pulse generator 116 a, this clock pulse generator 116 a stopsthe output of the clock signal CLK or stops the oscillating operationthereof so as to stop the supply of the clock signal.

In FIG. 1, the reference numeral 120 designates a power supply circuit.In the second data processor 101, the operation power vdd1 of the switchcircuit 114 and the operation power vdd2 of the other circuits can beisolated from each other. For example, an external power supply terminaland a power supply wiring of the operation power vdd1 and an externalpower supply terminal and a power supply wiring of the operation powervdd2 may be isolated physically. The power supply circuit 120 suppliesthe operation power vdd1 and vdd2 to the corresponding power supplyterminals. The general purpose input/output port 116 b is used as apower supply control circuit for the power supply circuit 120. Thegeneral purpose input/output port 116 b stops supply of the operationpower vdd2 to the entire part or a part of the other circuits during theperiod where the second data processor 101 shifts to the waitingcondition. The operation power vdd1 is always supplied to the switchcircuit 114 when the second data processor 101 can operate. When thesecond data processor 101 goes out of the waiting condition through theinterruption process, the operation power is supplied to an interruptioncontrol circuit. The power supply control circuit 116 b sets the powersupply control register of the power supply circuit 120 to the powersource supply stop instructing condition during transition to thewaiting condition. Accordingly, supply of the operation power vdd2 isstopped. Here, it is sufficient that the reset operation to the powersource supply instructing condition for the power supply controlregister is performed during the recovery process to the operatingcondition from the waiting condition.

FIG. 2 illustrates an example of detailed circuits provided in theregion 118 of the second data processor 101 of FIG. 1. Moreover, in thisexample, the first external interface circuit 119 is connected as a busmaster of the internal low-speed bus 115 with a signal line 200. Asillustrated by the signal line 200 of FIG. 2, the internal bus throughwhich the first external interface circuit 119 operates as a bus masteris not limited to control of the high-speed bus 108, but this techniquemay be applied to the low-speed bus 115 as well.

In the data processor 101, a circuit formed in the region 118 is calleda second circuit, while a circuit, such as the CPU 109 that is formed inthe other region, is called a first circuit. The region 118 includes afirst external terminal 210, a first bus 211 for connecting the firstexternal terminal 210 and the first circuit, a second bus 212 forconnecting the first circuit and the second circuit, a third bus 213 forconnecting the first external terminal and the second circuit, a secondexternal terminal 215, a fourth bus 216 for connecting the secondexternal terminal and the second circuit, a selector 217 for selectingany one of the second bus 212 and third bus 213 for connection to thefourth bus 216, a bus driver 218, and a fifth bus 219. The selector 217selects the connection profile to connect the first bus 211 via thethird bus 213 to the fourth bus 216 during the period of transition tothe waiting condition. When attention is given to the condition of CPU109, execution of an instruction by the first circuit is controlled(first condition) in the waiting condition, while an instruction isexecuted by the first circuit (second condition) in the operatingcondition. In the waiting condition, the second data processor 101 canconnect the first external bus 103 directly to the second external bus105. In this example, data of the first external bus 103 is transferred,without any change in condition, to the second external bus 105 in thewaiting condition of the second data processor 101, but it is alsopossible to connect the first external bus 103 and second external bus105 by way of an input/output buffer (not illustrated). Accordingly,input/output data to the second external bus 105 from the first externalbus 103 can be controlled.

In FIG. 1 and FIG. 2, the second data processor 101 is formed as aso-called single chip data processor that is formed on one semiconductorsubstrate.

FIG. 3 illustrates an example where a second data processor 300 isconfigured as a multi-chip module. The second data processor 300 iscomposed of the first external interface circuit 119, a chip 301 havingthe function of the switch circuit 114 and a chip 302 having the otherfunctions. The chip 302 has a connecting unit 303 to the internalhigh-speed bus 108 serving as the first external interface circuit 119,and the chip 301 connected to the connecting unit 303 can be operated asthe bus master of the internal high-speed bus 108. The first externalbus 103 can be connected to the second external bus 105 by operatingonly the chip 301 in the waiting condition of the second data processor300.

FIG. 4 illustrates a practical example of the first external interface119 of the second data processor 101. The first external interfacecircuit 119 is composed of an external bus access control unit 401, abus conversion adjusting unit 402, an internal bus access control unit403, a RAM access control unit 404 and a reset/interruption control unit405.

The access information from the first external bus 103 is inputted tothe external bus access control unit 401 and is then transferred to thebus conversion adjusting unit 402 through synchronization of the inputinformation. The bus conversion adjusting unit judges whether therelevant access is to be made to the RAM 107 or to the internal bus 108.When this access is issued to the internal bus 108, an access request isoutputted to the internal bus access control unit 403 to drive the busaccess operation, depending on the bus access specification of theinternal bus 108. In short, the address signal, bus access controlsignal and data are supplied to the bus 108, conforming to the busaccess specification of the internal bus 108, and, moreover, data isreceived from the bus 108. When an access request is issued to the RAM107, a memory access request is sent to the RAM access control unit 404to drive the access operation conforming to the access specification ofthe RAM 107. In short, the address signal, memory control signal anddata are supplied to the RAM 107 conforming to the memory accessspecification, and, moreover, data is received from the RAM 107.

Issuance of an interruption/reset instruction to the CPU 109 and aninterruption instruction from the CPU 109 are processed in thereset/interruption control unit 405, and the external bus access controlunit 401 issues the corresponding request to the device on the firstexternal bus 103. Moreover, the request from the device on the firstexternal bus 103 and the operation request from the RAM access controlunit 404 are given, by the external bus access control unit 401, to thereset/interruption control unit 405 as a corresponding interruptionrequest.

FIG. 5 illustrates another practical example of the first externalinterface 119 of the second data processor 101. In this figure, apractical example to realize an interface for the bus 103, an interfacefor the bus 115 and an interface for the RAM 107 is illustrated. Thefirst external interface circuit 119 includes a control circuit 410, anindex register IDX and an address flag FG. The control circuit 410includes a register comprising a built-in control circuit, such as anaddress register ADR, a data register DAT, a command register CMD, anaccess control register ACS and a status register STS. The address flagFG designates selection of the index register IDX when the logical value“1” is set, and it designates selection of the register comprising thebuilt-in control circuit when the logical value “0” is set. Whichregister should be selected among the registers comprising a built-incontrol circuit, when the logical value “0” is set, is determined withthe value of the index register IDX. The index register IDX and addressflag FG are accessed via the first external bus 103. The bus 103 iscomposed of a data bus 103D, an address bus 103A and a control bus 103C.The register comprising a built-in control circuit is selected dependingon the value of the index register IDX, and the address information,data information, bus access control information and command informationare loaded to the corresponding register via the data bus 103D, andaccess to the RAM 107 and access to the bus 115 are driven depending onthe command information that is loaded. For the access, in this case, asetting value of the register is used, and the access timing isdetermined on the basis of the access control information. The datawritten to the RAM 107 via the external bus 103 can be accessed from theCPU 109 via the internal bus 108. The bus 108 is composed of a data bus108D, an address bus 108A and a control bus 108C. The bus 115 iscomposed of a data bus 115D, an address bus 115A and a control bus 115C.

FIG. 6 illustrates an example of the initial writing of a boot programof the data process in the data processing system of the presentinvention. In the example of FIG. 6, a memory 502 is allocated in theinternal bus 115 of the CPU 109, and, moreover, a memory 501 is alsoallocated in the second external bus 105. In this example, although theinvention is not particularly so restricted, the memories 501, 502 areused as the user program storage regions. In this case, the boot programexecuted immediately after the second data processor 101 is reset isusually stored in the memory 501 or 502. In FIG. 6, the internal memory502 is connected to the internal low-speed bus 115, but it may also beconnected to the internal high-speed bus 108. The internal memory 502 ofthe second data processor is an electrically reprogrammable nonvolatilememory, such as a flash memory, and may be formed on one semiconductorsubstrate together with the CPU 109 or the like, or it may be formed ona different semiconductor substrate and also may be sealed in onepackage. When it is formed on a different semiconductor substrate and isthen sealed in one package, it may be connected, within the package, tothe second external bus 105 in place of connection to the internal buses108, 115 of the second data processor 101. Here, the electricallyreprogrammable nonvolatile memories 501 and 502 are used as the programmemory.

The initial writing of a program to the electrically reprogrammablenonvolatile memories 501, 502 has been performed using a writing device,such as an EPROM writer, in the fabrication process of the semiconductorintegrated circuit, such as data processor 101. The example of FIG. 6 isbased on the assumption that a boot program is not initially written inthe nonvolatile memories 501, 502 in the initial stage, where the dataprocessor 101 is mounted on the data processing system. The dataprocessing system of FIG. 6 enables the initial write operation of theboot program from such initial stage. In short, the system for bootingthe second data processor 101 from the RAM 107 is comprised within thesecond data processor 101. Namely, the boot program of the second dataprocessor 101 is written to the RAM 107 from the first data processor100 via the first external bus 103 to control the second data processor101 to execute the program of the RAM 107 after such a write operation.For this purpose, switching is required to drive the second dataprocessor 101 with execution of the program of the RAM 107 or withexecution of the program of the memory 501 or 502. This switchingoperation is performed using the level of a boot mode signal (BT) 503when a reset signal (RES) 504 instructs the reset operation. Forexample, when the boot mode signal 503 is in the high level during theperiod where the reset signal 504 is in the low level, the switching isdriven by execution of the program of RAM 107; while, when the boot modesignal 503 is in the low level, the switching is driven by execution ofthe program of the memories 501, 502.

A structure for the initial write operation of the boot program will bedescribed in detail. In the second data processor 101, the RAM 107 isset to the write-ready condition by the first data processor 100 in thefirst operation mode after the reset operation is cancelled by the resetsignal 504. In the first operation mode, the boot mode signal 503 is setto the high level, for example, during the reset period where the resetsignal 504 is set in the low level, and, thereby, the reset signal 504is negated to the high level to cancel the reset operation. In thiscase, the CPU 109 is controlled in the instruction fetch. In short,supply of a start vector to the CPU 109 is controlled. As describedabove, in this case, the access to RAM 107 is extended to the firstexternal interface circuit 106 by the first data processor 100. When thewrite operation to the RAM 107 by the data processor 100 is completed,the start vector for designating the leading address of the RAM 107 issupplied to the CPU 109 with the command given to the first externalinterface circuit 119 from the data processor 100, or in response to achange of the boot mode signal 503 to the low level from the high level.Accordingly, the CPU 109 executes the program stored in the RAM 107.Here, since attention is paid to the initial write operation of a userprogram, it is sufficient when the program stored in the RAM 107 is atleast the write control program of the user program. The user programitself may be transferred previously to the RAM 107 together with theprogram described above. Otherwise, it is also possible to initiallywrite the user program to the memory 502 by reading this program fromthe serial interface circuit 116 or the like through execution of thewrite control program transferred to the RAM 107.

In the second operation mode, after the reset operation is cancelled,the memory 501 or 502 is considered as the object of instruction fetchwith the CPU 109. In the second operation mode, the boot mode signal 503is set to the low level and the reset signal 504 is negated to the highlevel during the period where the reset signal 504, for example, is setto the low level, and, thereby, the reset operation is cancelled.Accordingly, the CPU 109 executes the user program initially stored inthe memory 501 or 502 via the first operation mode.

The operation for storing the program for write control as the bootprogram to the RAM 107 from the first data processor 100 will bedescribed.

First, prior to the booting of the second data processor 101, the bootprogram inputted from the external storage, such as memory 505 or memorycard 506 connected to the first data processor 100, or from the serialinterface (not illustrated), is written by the first data processor 100to the RAM 107 of the second data processor 101.

The boot program transferred to the RAM 107 may include up to theapplication, but a short boot program may be used when it includes thefollowing processes. For example, the programs to be written to thememory 501 or 502 are stored to the program on the RAM 107 through thetransfer of programs via the first external interface circuit 119 fromthe first data processor 100. Otherwise, the programs to be written bytransferring a program to the memories 501, 502 are stored using theserial bus, USB terminals or memory card of the peripheral device 116 ofthe second data processor.

From the above description, when the memories 501, 502 for boot of thesecond data processor 101 are flash memories, a system for initializingthe flash memory has been required intrinsically in the post-process ofthe system assembling, but since the flash memory can be initialized inthe mode for booting from the RAM 107, the mass-production cost of thedata processor 101 can be reduced.

FIG. 7 illustrates an example of a timing diagram of the boot operationin the data processing system of FIG. 6.

The first data processor 100 supplies a boot mode signal 503 and a resetsignal 504 to control the drive of the second data processor 101.

When the first data processor sets the boot mode signal 503 to the highlevel to cancel the reset (the reset signal shifts to the high levelfrom the low level) and, thereby, the second data processor is driven inthe boot mode from the RAM 107, the boot program is transferred to theRAM 107 via the first external bus 103. The CPU 109 of the second dataprocessor detects that the boot mode signal is in the high level, andthe boot program is fetched from the RAM 107 via the first externalinterface circuit 119. The CPU 109 is controlled to perform theinstruction fetch during transfer of the boot program and is, therefore,set in the waiting condition because the boot program is not suppliedthereto. Upon completion of transfer of the boot program, the first dataprocessor 100 transfers the transfer completion command to the firstexternal interface circuit 119; and, when the first external interfacecircuit 119 instructs fetch of the boot program to the CPU 109, thesecond data processor 101 is driven with the program of RAM 107. The CPU109 executes the boot program in the RAM 107 and performs the writeprocess of the boot program to the memories 501, 502 via the internalhigh-speed bus 108. When the write process of the boot program to thememories 502, 502 is completed, the second data processor 101 is resetagain (reset signal (RES) 504 is shifted to the low level from the highlevel) and this reset is cancelled under the condition that the bootmode signal (BT) 503 is set to the low level to drive the second dataprocessor 101. Accordingly, the CPU 109 fetches the boot program fromthe memories 501, 502 to execute this program, and, thereby, the dataprocessing operation of the second data processor is driven.

FIG. 7 illustrates an example of the operation timing to supply the bootprogram to the memories 501, 502 from the memory 505 or memory card 506connected to the first data processor 100 via the first external bus103.

FIG. 8 illustrates an example of another timing diagram of the bootoperation in the data processing system of FIG. 6. The timingillustrated in FIG. 8 assumes that the boot program stored in thememories 501, 502 is supplied via the serial and USB terminals 116 orthe like of the second data processor 101. The other timings are same asthose of FIG. 7.

FIG. 9 illustrates an example of the timing diagram when the bootprogram is updated or the application executed by the second dataprocessor 101 is added/updated under the condition that the boot programis stored in the memory 501 or 502.

When the first data processor 100 sets the boot mode signal 503 to thelow level to cancel the reset, the second data processor 101 starts thedrive by fetching the boot program from the memories 501, 502. Thememories 501, 502 previously store the transfer program for update ofthe boot program or addition/update of the application executed by theprocessor 2, and the transfer program is driven with a drive instructionor the like from the first data processor 100. For example, theapplication for addition is received through radio communication via anantenna connected, for example, to the first data processor 100, and thefirst data processor 100 transfers the received application for additionto the RAM 107 via the external bus 103. The second data processor 101fetches the application for addition stored in the RAM 107 to theinternal bus 108 via the first external interface circuit 119 and, then,transfers this application to the memory 501 or 502 for the writeoperation.

FIG. 10 illustrates an example of the cross-sectional view of amulti-chip module forming the data processor 300 of FIG. 3. On one planeof a high density mounting board 510, many bump electrodes 511,connected to the mounting surface of a printed circuit board, which isformed of a glass epoxy substrate, are allocated, while, on the otherplane, many micro-bump electrodes 512 and pad electrodes 513, which areconnected to the bump electrodes 511, are allocated. At apart of themicro-bump electrodes 512, a bonding pad of the semiconductor chip 302is mounted on a face-down basis. The other semiconductor chip 301 isstacked for allocation on the semiconductor chip 302, and the bondingpad of this semiconductor chip 301 is connected to the corresponding padelectrode 513 with a bonding wire 515. The entire part of the bondingwire 515 and semiconductor chips 301, 302 is molded with resin 516.

The present invention has been described on the basis of a preferredembodiment thereof, but the present invention is not limited thereto, sothat various changes and modifications are possible within the scope ofthe claims.

For example, the peripheral circuits and the other circuit modulescomprised in the data processor are not limited to those described withreference to FIG. 1, and they may be changed as required. The internalbuses of the data processor need not be provided as a high-speed bus andlow-speed bus. In addition, the operation supply systems for the firstcircuit and second circuit are not always separated from the externalpower source terminals, and stopping of supply of the power may becontrolled with a switch circuit. In addition, when the data processoris formed as a multi-chip module, the kind of the semiconductorintegrated circuit to be loaded is not limited only to that describedabove, and three chips in total, such as a semiconductor chip like theflash memory 502, a processor core chip, such as the other CPU 109, andan interface chip like the semiconductor chip 301 may be mounted. Aplurality of flash memory chips may also be mounted to the multi-chipmodule.

As described above, the present invention may be widely applied to adata processing system which is intended to effect dispersion ofprocessing loads using a plurality of data processors, such as a mobilephone system, display control system, printer system and the othermobile information terminals, and to a data processor which utilizessuch a data processing system.

What is claimed is:
 1. A data processing system comprising: a firstsingle chip data processor; a second single chip data processorincluding a central processing unit (CPU), a first external interfacecircuit, an internal bus coupled to the CPU and the first externalinterface circuit, and an internal circuit; an external device; a firstexternal bus coupled to the first and second single chip data processor;and a second external bus coupled to the second single chip dataprocessor and the external device, wherein the internal circuit iscoupled to the first external bus and the second external bus, whereinthe second single chip data processor has a standby mode in which poweris supplied to the internal circuit and power is not supplied to thefirst external interface, and has an operating mode in which power issupplied to the second single chip data processor and the CPU fetches aninstruction, wherein, when the second single chip data processor is inthe operating mode, the first data processor accesses the second dataprocessor through the first external interface circuit and the seconddata processor supplies a signal to the second external bus, andwherein, when the second single chip data processor is in the standbymode, the first data processor accesses the external device through theinternal circuit.
 2. The data processing system according to claim 1,wherein the external device is LCD controller, and wherein, when thesecond data processor is in the standby mode, the first data processorprocesses a time display control for the LCD controller through theinternal circuit.
 3. The data processing system according to claim 2,wherein the first data processor is baseband processor.
 4. The dataprocessing system according to claim 3, wherein, when the second dataprocessor is in the standby mode, the second data processor changes theoperating mode with an interrupt.